An integrated anti-radiation stray light receiving device

Abstract

The application belongs to the field of laser detection technology and laser fuze, and particularly relates to an integrated anti-radiation stray light receiving device, which comprises a detector, a bias circuit and an optical system; the bias circuit is connected with the P end and the N end of the detector respectively; the target surface of the detector corresponds to the output end of the optical system; the optical system comprises a first receiving lens, a second receiving lens, a light isolation barrel and a third receiving lens; the convex end of the second receiving lens corresponds to the concave end of the first receiving lens, and the light isolation barrel is arranged between the second receiving lens and the third receiving lens; a narrowband filter film is coated on the surface of the second receiving lens; the third receiving lens is used for finally converging the light beams in the field of view to the target surface of the detector; the application adopts an integrated structure design, executes three measures of light, machinery and electricity, and improves the detection capability and anti-interference capability of the receiving module on the basis of a low-cost thought.

Description

Technical Field

[0001] This invention belongs to the fields of laser detection technology and laser fuses, and specifically relates to an integrated anti-radiation stray light receiving device. Background Technology

[0002] Laser detection technology employs an active detection mode and a pulsed operating system, possessing the primary functions of short-range target identification, ranging, and azimuth recognition. It detects targets and backgrounds within a defined field of view using lasers, outputting echo signals for subsequent signal processing circuitry. Due to its strong electronic countermeasures capabilities and high ranging accuracy, laser detection technology is widely used in various fields. Laser short-range detection is one of the typical applications of laser detection technology. With the increasing diversification of targets and the complexity of working environments, the laser short-range detection front-end device, as the core functional component of laser short-range detection, needs to improve its detection capabilities and anti-interference capabilities to promote the rapid development of the optoelectronic detection market.

[0003] Laser short-range detection devices are generally front-side detection devices, using a 360° circumferential continuous field of view to detect targets. This means that direct sunlight, reflected light from clouds, the ground, or the sea can easily enter the optical field of view of the receiving device, turning into strong background noise that "blinds" the system and significantly reducing the laser detection capability. At the same time, as a photoelectric detection device with a large field of view and a large dynamic range, all abnormal transmitted light (stray light) in the optical system of the laser receiving module will affect the signal-to-noise ratio of the detection system to a certain extent, reducing the laser detection's anti-interference capability. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes an integrated anti-radiation stray light receiving device, comprising: a detector, a bias circuit, and an optical system; the bias circuit is connected to the detector, and the bias circuit reduces the current-limiting resistor of the detector and increases the bias voltage of the detector; the target surface of the detector corresponds to the output end of the optical system; the optical system includes a first receiving lens, a second receiving lens, a light-blocking barrel, and a third receiving lens; wherein the convex end of the second receiving lens corresponds to the concave end of the first receiving lens, and the light-blocking barrel is disposed between the second receiving lens and the third receiving lens; the third receiving lens is used to converge the light beam within the field of view onto the detector target surface.

[0005] Preferably, the design rules for the detector and optical system satisfy:

[0006] y=ftanθ

[0007] Where y is the radius of the detector target surface, f is the focal length of the optical system, and θ is the field of view of the receiving system.

[0008] Preferably, the first receiving lens, the second receiving lens, and the third receiving lens in the optical system are all thin lenses, and their variable properties and power distribution principles are as follows:

[0009]

[0010]

[0011]

[0012] H1D1+H2D2+H3D3=H1D

[0013] Among them, S I C is the primary field curvature coefficient. I C is the primary position color difference coefficient. II The primary magnification chromatic aberration coefficients are given by: D1, D2, D3, and D, representing the optical power and total optical power of the three receiving lenses, respectively; (n1, β1), (n2, β2), and (n3, β3), representing the refractive index and Abbe number of the three receiving lenses, respectively; (H1, H... p1 (H2, H) p2 ) and (H3, H p3 These represent the projection heights of the paraxial ray at the edge of the on-axis point and the principal ray of the maximum field of view on the three lenses, respectively.

[0014] Preferably, the capacitor consists of a first capacitor C1, a second capacitor C2, a resistor R1, a resistor R2, a third capacitor C3, and a fourth capacitor C4. One end of the first capacitor C1 is grounded, and the other end is connected to the bias input terminal, one end of the second capacitor C2, and one end of the resistor R2. The other end of the second capacitor C2 is grounded. The other end of the resistor R2 is connected to the fourth capacitor C4 and the N terminal of the detector. The other end of the fourth capacitor C4 is grounded. One end of the resistor R1 is connected to the P terminal of the detector, and the other end is grounded. One end of the third capacitor C3 is connected to the P terminal of the detector, and the other end is connected to the input terminal of the amplifier circuit.

[0015] Furthermore, the voltage applied across the probe is:

[0016] V PD =V R -(R1+R2)i e

[0017] Among them, V R Indicates power supply, i e R1 represents the background photocurrent, R2 represents the current-limiting resistor, and R2 represents the sampling resistor.

[0018] Preferably, the spectral bandwidth of the optical system meets a specific condition, namely, the narrowband transmission filter of the optical system is:

[0019]

[0020] Where, τ s τ represents the transmittance of the filter within the suppressed spectral range. p Δλ represents peak transmittance, Δλ represents sharpness factor, S represents narrowband bandwidth, and λ represents peak transmittance. c Indicates the center wavelength of the passband.

[0021] Preferably, each optical component in the optical system has an anti-reflection coating on its surface and a matte black paint on its edge. The anti-reflection coating is used to increase the optical transmittance of the component, and the matte black paint is used to eliminate stray light.

[0022] Preferably, the optical system has a multi-stage anti-stray light aperture in the light-blocking barrel, which increases the reflection path of abnormal optical paths.

[0023] The beneficial effects of this invention are:

[0024] This invention employs an integrated structural design, implementing opto-mechanical-electronic measures while adhering to a low-cost philosophy. It enhances the detection and anti-interference capabilities of the receiving module, meeting the engineering application requirements for adaptability to complex environments in forward detection systems. Structurally, the invention utilizes an integrated opto-mechanical-electronic design to meet the needs of miniaturization and versatility in engineering applications. The invention incorporates a narrowband filter design, compressing the narrowband bandwidth through multi-stage angle transmission to improve the radiation resistance of the receiving system. Furthermore, the invention utilizes a bias circuit to reduce the current-limiting resistor and sampling resistor of the detector, thereby improving radiation resistance. Finally, the invention adds a light-blocking barrel, employing multi-stage attenuation to suppress stray light, further enhancing the anti-interference capability of the receiving system. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the integrated receiving device structure of the present invention;

[0026] Figure 2 This is a structural diagram of the receiving optical system of the present invention;

[0027] Figure 3 This is a transmittance curve of the narrowband filter spectrum of the present invention;

[0028] Figure 4 This is a schematic diagram of the detector bias circuit of the present invention;

[0029] Figure 5 This is a simulation analysis diagram of stray light in the receiving optical system of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] An integrated anti-stray light receiving device includes a detector, a bias circuit, and an optical system. The bias circuit is connected to the detector and reduces the current-limiting resistor and increases the bias voltage of the detector. The target surface of the detector corresponds to the output end of the optical system. The optical system includes a first receiving lens, a second receiving lens, a light-blocking barrel, and a third receiving lens. The convex end of the second receiving lens corresponds to the concave end of the first receiving lens, and the light-blocking barrel is disposed between the second and third receiving lenses. The third receiving lens is used to converge the light beam within the field of view onto the detector target surface.

[0032] A specific embodiment of an integrated anti-stray light receiving device is described. The method comprises six parts: a detector module with integrated detection and amplification, receiving lens 1, receiving lens 2, receiving lens 3, a light-blocking barrel, and a support frame. A cross-sectional view of the structure is shown below. Figure 1 As shown. The receiving lens is used to focus the light beam within the field of view onto the detector target surface; the detector module realizes photoelectric conversion and amplifies the output; the light-blocking barrel is used to suppress stray light; the bracket is used to mechanically connect the lens, detector module, light-blocking barrel, etc.

[0033] The sun is the strongest natural infrared broadband radiation source. The total irradiance produced by the sun on Earth is 1353W / m2. The sun's energy is mainly concentrated in the 0.217-10.94μm band. About 50% of its spectrum is distributed in the infrared region, 40% in the visible light region, and it has a relatively strong radiation energy in the 905nm working band.

[0034] The analysis considers the worst-case scenario of direct sunlight irradiance on the optical receiving system. The peak value of the spectral radiance of sunlight is: M λm =BT 5 =9.2×10 7 Wm -2 μm -1 Its near-infrared spectral radiative exitance is approximately: M λ =f(λT)M λm =2.9×10 7 Wm -2 μm -1 Therefore, the δλ radiation intensity within the passband of the near-infrared narrowband filter satisfies the following expression:

[0035] M δλ =M λ ×δλ

[0036] According to the above expression, when the effective aperture of the receiving optical system is fixed, the solar radiation power received by the detection system is mainly determined by the bandwidth of the narrowband filter.

[0037] To improve the fuse's resistance to sunlight background interference, the bandwidth of the filter should be compressed as much as possible. The bandwidth of a narrowband filter is mainly determined by two factors: the spectral range of the laser emission source and the incident angle range of the filter. Since the laser detection source uses a 905nm semiconductor laser, its spectral range shift reaches 35nm across the entire operating temperature range. Therefore, in the design of a wide-field-of-view receiving optical system, the surface with the smallest incident angle range should be selected for the film design.

[0038] The design rules for detectors and optical systems satisfy:

[0039] y=ftanθ

[0040] Where y is the radius of the detector target surface, f is the focal length of the optical system, and θ is the field of view of the receiving system.

[0041] The first, second, and third receiving lenses in the optical system are all thin lenses, and their variable properties and the principle for allocating optical power are as follows:

[0042]

[0043]

[0044]

[0045] H1D1+H2D2+H3D3=H1D

[0046] Among them, S I C is the primary field curvature coefficient. I C is the primary position color difference coefficient. II The primary magnification chromatic aberration coefficients are given by: D1, D2, D3, and D, representing the optical power and total optical power of the three receiving lenses, respectively; (n1, β1), (n2, β2), and (n3, β3), representing the refractive index and Abbe number of the three receiving lenses, respectively; (H1, H... p1 (H2, H) p2 ) and (H3, H p3 These represent the projection heights of the paraxial ray at the edge of the on-axis point and the principal ray of the maximum field of view on the three lenses, respectively.

[0047] By solving the above formulas, the power distribution of the three lenses is obtained, serving as the initial structure of the optical system. The optimal solution is then obtained by forward optimization to balance primary and higher-order aberrations. This method simplifies the tedious steps of solving the seven aberration equations in primary aberration theory, gradually guiding the evaluation function to its optimal solution using empirical values. The method is simple, and the optimization results are more accurate.

[0048] like Figure 2 As shown, when the refractive index of the film material is the same, the exit surface of the second lens with a smaller range of incident angle variation is selected to fabricate the filter to reduce the drift of the passband peak point, thereby further reducing the filter bandwidth. The narrowband transmittance design meets the following requirements:

[0049]

[0050] Where, τ s τ represents the transmittance of the filter within the suppressed spectral range. p Δλ represents peak transmittance, Δλ represents sharpness factor, S represents narrowband bandwidth, and λ represents peak transmittance. c Indicates the center wavelength of the passband.

[0051] The transmittance curves of the narrowband filter film with incident angles of 0° to 45° were obtained through simulation, such as... Figure 3 As shown, the center wavelength shift caused by the incident angle is 65nm, and the temperature drift of a 905nm semiconductor laser is 35nm. Therefore, within the operating temperature range of -45℃ to +75℃, the narrowband bandwidth is designed to be 100nm to meet the engineering application requirements of a continuous 90° detection field of view.

[0052] like Figure 4 As shown, the bias circuit includes a first capacitor C1, a second capacitor C2, resistors R1 and R2, a third capacitor C3, and a fourth capacitor C4. One end of the first capacitor C1 is grounded, and the other end is connected to the bias input terminal, one end of the second capacitor C2, and one end of resistor R2. The other end of the second capacitor C2 is grounded. The other end of resistor R2 is connected to the fourth capacitor C4 and the N terminal of the detector. The other end of the fourth capacitor C4 is grounded. One end of resistor R1 is connected to the P terminal of the detector, and the other end is grounded. One end of the third capacitor C3 is connected to the P terminal of the detector, and the other end is connected to the input terminal of the amplifier circuit. The voltage applied across the detector is:

[0053] V PD =V R -(R1+R2)i e

[0054] Among them, V R Indicates power supply, i e R1 represents the background photocurrent, R2 represents the current-limiting resistor, and R2 represents the sampling resistor.

[0055] Due to the influence of the ambient background, while converting the useful pulse light signal, the detector also converts the background light illuminating the detector into a background photocurrent ie. The background photocurrent ie will create a voltage drop ΔV = (R1+R2)×ie across R2 and R1. Therefore, under strong background light, the background photocurrent ie is larger, and the resulting voltage drop ΔV is larger, leading to a lower reverse bias voltage (VR-ΔV) of the detector, or even zero. This results in a decrease in the detector's responsivity and an increase in response time, causing the useful pulse light signal to weaken or be submerged in the background signal, resulting in a "blinding" phenomenon.

[0056] To ensure the high bandwidth requirements of the detector, an external bias operating voltage is needed. This power supply voltage is filtered by C1 and C2. To suppress crosstalk caused by the common path of the pulse current signal, a first-order low-pass filter circuit using R2 and C4 is used in the bypass circuit. Sunlight radiation has a wide spectrum, and its response on the detector is a DC voltage drop. When sunlight radiation is strong enough, the entire bias voltage drop falls across R2, resulting in zero voltage across the detector, no noise, no signal output, and the detection system becoming "blinded." To avoid this, the bias voltage is typically increased and the resistance is decreased. Increasing the bias voltage is directly proportional to the radiation resistance; the bias voltage value must be appropriately selected based on the overall power consumption. The resistance value is inversely proportional to the radiation resistance; decreasing the resistance value will increase the low-pass cutoff frequency of the pulse signal, resulting in an incomplete output signal waveform. With the bias voltage unchanged, an appropriate resistance should be selected based on the bandwidth of the pulse signal.

[0057] Stray light is a general term for all abnormally transmitted light in an optical system. Stray light is essentially noise in the optical system and can affect the signal-to-noise ratio to some extent. Laser short-range detection, as a photoelectric detection device with a large field of view and large dynamic range, incorporates stray light suppression design along the transmission path of the receiving optical path. To enhance the device's stray light resistance, the following design is implemented:

[0058] 1) The surface of the optical components is coated with an anti-reflective film, and the outer edges of the optical components are coated with matte black paint;

[0059] Partial reflection from the lens surface also forms a stray light transmission path. Therefore, the performance of antireflective coatings in optical components has a significant impact on stray light transmission, necessitating the design of antireflective coatings on the lens surface. Based on current optical film processing capabilities, the transmittance of optical antireflective coatings can reach 99%, which meets engineering application requirements.

[0060] 2) The inner wall of the optical cavity lens barrel is sandblasted and oxidized, and then coated with an anti-stray coating;

[0061] Most stray light is reflected by the structural tube of the receiving optical system; therefore, the construction and optical properties of the inner wall of the tube play a crucial role in the stray light coefficient. The optical properties of the tube surface have a significant impact on the stray light coefficient. To reduce stray light, it is important to make it as close as possible to a Lambertian diffuse reflector, such as by using sandblasting and oxidation treatment.

[0062] 3) An optical shield is added inside the optical cavity.

[0063] To further improve stray light suppression, a multi-stage anti-stray light aperture is placed in the optical barrel. The aperture increases the reflection path of abnormal optical paths, and the surface reflectivity is reduced by processes such as sandblasting and blackening. The reflectivity in the visible and near-infrared bands reaches less than 3%, which can significantly reduce the probability of stray light being transmitted backward into the photosensitive surface of the detector.

[0064] By employing the above three measures to suppress stray light, and comprehensively simulating optics, such as... Figure 5 As shown, the optics uses three lenses to achieve a 60° detection field of view. The internal structure is designed with a light-blocking barrel. This structure has four apertures in the optical transmission path, each aperture is arranged at a 0.5mm interval, and the groove depth at the aperture interval is 5mm. Through the design of the light-blocking barrel and the anti-reflection coating of the lens, the proportion of stray light can be suppressed to less than 1%.

[0065] The above-described embodiments further illustrate the purpose, technical solution, and advantages of the present invention. It should be understood that the above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An integrated anti-radiation stray light receiving device, characterized in that, include: Detector, bias circuit, and optical system; The bias circuit is connected to the P-terminal and N-terminal of the detector, respectively; the target surface of the detector corresponds to the output terminal of the optical system; the optical system includes a first receiving lens, a second receiving lens, a light-blocking barrel, and a third receiving lens; wherein the convex end of the second receiving lens corresponds to the concave end of the first receiving lens, and the light-blocking barrel is disposed between the second receiving lens and the third receiving lens; a narrow-band filter film is coated on the surface of the second receiving lens; the third receiving lens is used to finally converge the light beam in the field of view onto the detector target surface. The bias circuit includes a first capacitor C1, a second capacitor C2, resistors R1 and R2, a third capacitor C3, and a fourth capacitor C4. One end of the first capacitor C1 is grounded, and the other end is connected to the bias input terminal, one end of the second capacitor C2, and one end of resistor R2. The other end of the second capacitor C2 is grounded. The other end of resistor R2 is connected to the fourth capacitor C4 and the N terminal of the detector. The other end of the fourth capacitor C4 is grounded. One end of resistor R1 is connected to the P terminal of the detector, and the other end is grounded. One end of the third capacitor C3 is connected to the P terminal of the detector, and the other end is connected to the input terminal of the amplifier circuit. The voltage applied across the detector is: ； in, Indicates power supply. Indicates background photocurrent. Indicates the current-limiting resistor. Indicates the sampling resistor; The optical system has four apertures in the light-blocking barrel, each aperture is arranged at a 0.5mm interval, and the groove depth at the aperture interval is 5mm.

2. The integrated anti-radiation stray light receiving device according to claim 1, characterized in that, The design rules for detectors and optical systems satisfy: ； in, The radius of the detector target surface, For the focal length of the optical system, This represents the field of view of the receiving system.

3. The integrated anti-radiation stray light receiving device according to claim 1, characterized in that, The first, second, and third receiving lenses in the optical system are all thin lenses, and their variable properties and the principle for allocating optical power are as follows: ； ； ； ； in, For the primary field curvature coefficient, This is the primary position color difference coefficient. This is the primary magnification color difference coefficient. , , and These are the optical power and total optical power of the three receiving lenses, respectively. , ), ( , )and( , The refractive indices and Abbe numbers of the three receiving lenses are respectively. , ), ( , )and( , These represent the projection heights of the paraxial ray at the edge of the on-axis point and the principal ray of the maximum field of view on the three lenses, respectively.

4. The integrated anti-radiation stray light receiving device according to claim 1, characterized in that, The spectral bandwidth of the optical system satisfies a specific condition, namely, the narrowband transmission filter of the optical system is: ； in, This indicates the transmittance of the filter within the suppressed spectral range. Indicates peak transmittance. This represents the sharpness factor, where S represents the narrowband bandwidth. Indicates the center wavelength of the passband.

5. The integrated anti-radiation stray light receiving device according to claim 1, characterized in that, The surfaces of each optical component in the optical system are coated with an anti-reflective coating, and the edges of the optical components are coated with matte black paint. The anti-reflective coating is used to increase the optical transmittance of the components, and the matte black paint is used to eliminate stray light.

6. The integrated anti-radiation stray light receiving device according to claim 1, characterized in that, The optical system has multiple stray light blocking apertures in its light-blocking barrel, which increase the reflection path of abnormal optical paths.

7. The integrated anti-radiation stray light receiving device according to claim 1, characterized in that, The integrated radiation-resistant stray light receiver also includes a support frame that encapsulates the optical system, light-shielding barrel, detector, and bias circuitry within a structural cavity, forming an integrated device.

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